In the field of photoelectric display technology, an organic light emitting device (referred to as OLED) has the advantages of active light emission, high brightness, high contrast, ultra thinness, low power consumption, wide view angle, wide working temperature range and the like, and is a widely used, advanced and novel flat panel display device.
However, due to the inherent characteristics of the organic material, the organic material is liable to absorb water and oxygen and is prone to loss and deterioration after being subjected to water and oxygen corrosion, such that the service life of the device is greatly influenced, and accordingly the OLED device has high requirements on encapsulation.
At present, the encapsulation technology of the OLED device has become more and more mature, and includes traditional encapsulation of a glass cover or a metal cover and a drying piece, face encapsulation (Face Encap), frit encapsulation (Frit Encap), thin film encapsulation (TFE, Thin Film Encap), etc.
The thin film encapsulation technology has prominent advantages of reducing the weight and thickness of the device, reducing encapsulation accessories, lowering the encapsulation cost, decreasing the width of an encapsulation edge, eliminating display dead angles, and improving the curling flexibility, etc.
The structure of the OLED subjected to the thin film encapsulation in the prior art is as shown in FIG. 1, which includes a substrate 1, an organic light emitting unit 2 arranged on the substrate 1 and a pre-encapsulation layer 3 covering the organic light emitting unit 2, wherein an organic thin film 5 is deposited on the pre-encapsulation layer 3 for encapsulation to form the organic light emitting device.
As shown in FIG. 2, a general organic light emitting unit 2 includes a first electrode 201, a second electrode 203 and an organic functional layer 202 between the first electrode and the second electrode, wherein the first electrode 201 and the second electrode 203 provide holes and electrons to the organic functional layer 202 for emitting light; a buffer layer 204 is arranged on the second electrode 203 for protection; an insulating layer 205 is arranged between the first electrode 201 and the organic functional layer 202.
The encapsulation layer 3 is deposited at lower power, in order to reduce the damage of the deposition process to the organic light emitting unit 2.
The organic thin film 5 is prepared by forming a fluidal organic matter into a film and curing (ultraviolet curing) the film, since the organic thin film may shrink or expand in the curing process, the organic thin film will drive the pre-encapsulation layer 3 to shrink or expand, so as to generate a stress on the organic light emitting unit 2, and the stress will damage the organic light emitting unit 2.
Meanwhile, the organic thin film 5 is liable to absorb water and oxygen to deform to generate loss, or the water and oxygen absorbed by the organic thin film 5 are further transferred to the organic light emitting unit 2 to shorten the service life of the organic light emitting unit 2.